1. Field of the Invention
The present invention relates to re-writeable non-volatile computer memory using mechanical components.
2. Description of the Related Art
Most computers have four types of necessary hardware components: CPU (central processing unit), input device, output device and memory. The CPU executes programs (software) which tell the computer what to do. Input and output (I/O) devices allow the computer to communicate with the user and the outside world. Memory enables a computer to store, at least temporarily, data and programs.
There are many ways in which memory can be categorized. For example, whether the CPU can directly or indirectly access the memory is the distinction between primary and secondary storage and whether the CPU can access any portion of the memory at any time or whether the data must be read in sequence is the distinction between random access media and sequential access media. However, these distinctions are typically necessitated by the underlying technology of the memory.
For example, certain types of memory, such as magnetic tape, are better suited to sequential access media. Similarly, if the underlying technology of a memory allows for very fast access, but loses its data when power is turned off (volatile memory), it may be appropriate for primary storage, but not secondary storage. If the underlying technology allows only slow access, but is non-volatile, secondary storage may be more appropriate. Cost concerns will also drive a technology's implementation. For example, read only memory is typically cheaper than rewritable memory, so it is used whenever data does not need to be changed.
One developing technology is named “Millipede” and is being developed by IBM's Zurich Research Laboratory, as described in “The millipede, a very dense, highly parallel scanning-probe data-storage system,” by G. Cherubini, et al. in European Solid-State Circuits Conference, September 2002, pp. 121-125, incorporated herein by reference for all purposes. The technology involves an atomic force microscopy (AFM) tip for reading and thermomechanical writing of topographical features for data storage. Thermomechanical writing is a combination of applying a local force by the cantilever/tip to a polymer layer and softening it by local heating. By applying sufficient heat, an indentation can be formed into the storage medium for writing a bit which can be read back with the same tip. The indentation can be sensed by the fact that the lever is bent when it is moved into the indentation, causing (either directly or indirectly) an electrical resistance change.
There are continuing efforts to improve upon the various memory technologies.
It is to be understood that, in the drawings, like reference numerals designate like structural elements. Also, it is understood that the depictions in the FIGS. are not necessarily to scale.